1. Field of the Invention:
This invention relates to a proteinous material. More particularly, it relates to a proteinous material which comprises partially denatured but not thermally decomposed fish proteins, i.e., partially decomposed fish proteins. The proteinous material of the present invention is suitable as a protein source for, e.g., foods, feeds, baits and pet foods.
2. Description of the Prior Art:
Conventional protein sources for, e.g., foods, feeds, baits and pet foods include vegetable proteinous materials such as soybeans, peanuts, cotton seeds, sesame seeds, sunflower seeds and wheat as well as defatted products obtained therefrom and materials derived therefrom and animal proteinous materials such as various milks, animal meat, fish meat, other meat and eggs as well as products obtained by processing them and materials derived therefrom. Further there are widely available proteinous materials separated from the abovementioned proteinous materials including vegetable proteins such as soybean protein and wheat protein and animal proteins such as casein, fish protein concentrate, which will be abbreviated as FPC hereinafter, and fish meal. Among these widely available proteinous materials, inexpensive vegetable ones are more frequently used However these vegetable proteins are inferior to animal ones in the nutritive value since the former contain less amounts of lysine and methionine in the amino acid composition, in particular essential amino acid component Therefore animal proteins such as fish meal are used as excellent protein sources in, for example, animal feeds Furthermore there have been provided fish meal and FPC as food products for man. However proteins contained in these fish proteinous materials for foods and feeds are thermally treated or treated with a solvent and not always satisfactory since they show poor digestibilities because thermally denatured or the free .epsilon.-amino group of lysine, which is considered to be effective as an essential amino acid binds to other active substances, which makes the proteinous materials hardly decomposable with digestive enzymes; or these products might contain trace amounts of residual solvents.